This isn’t earth-shattering news, but here’s the catch – all were in high school. Teen social media users seem to be flocking to Twitter right now, continuing a trend over the past two years, and reducing Facebook usage in favor of the 140-character social network. We’ve seen such a shift in preference before, when users flocked to Facebook over Myspace in 2007. History may be on the verge of another social platform shift, and brands can’t be caught flat-footed when it comes to marketing to the younger generation.

Why they’re choosing Twitter
According to an Associated Press report, Facebook’s generation-spanning popularity is partly to blame. In a world where it’s considered rude to turn down a friend request, especially from a family member, teens were suddenly seeing their aunts, uncles and parents in their News Feeds. Twitter connections aren’t mutual friendships as they are on Facebook; just because someone follows your tweets doesn’t mean you have to follow them back. Teenaged users like this feature, and they’re employing Twitter’s simpler privacy controls as well, choosing to hide their tweets from public view and sending them only to a select group of friends.

The type of interaction plays a major role as well, according to the teens I’ve met. To them, Facebook is more about sharing content, whether it’s videos, photos, music, or articles. Twitter is far more conversation based, a place where teens can tell their friends what they’re doing or how they feel. It’s about the present moment – what you’re doing, who you’re seeing, where you’re going – whereas Facebook is more about sharing memories after the fact.

Teens aren’t giving up on Facebook, but they’re treating it the same way the gainfully employed treat LinkedIn. They feel it’s important to maintain a page, but they check the social network sporadically. Twitter is where they go to check in throughout the day.

What Facebook can do
Facebook, with its 901 million active users, isn’t necessarily reeling simply because teens are adopting Twitter much faster then ever before, but marketers should be aware of the possibility that Facebook’s teen audience could shrink, or be less engaged than were prior generations. You can say “No one gets fired for buying Facebook,” but brands need to be sure to extend investment and innovation to Twitter — especially if they are marketing to teens.

Facebook needs to be mindful of the shift in teen usage as well, unless it wants to join Myspace in the social media dustbin. It might seem far-fetched to hint at Facebook’s decline, but it’s worth noting Myspace was getting more visitors than Facebook at one point in time. Myspace lost ground to Facebook because it failed to adapt. Facebook had a sleeker design — one that was less frantic, and contained fewer ads. Twitter’s main features may appear scrawny compared to Facebook’s, but it wouldn’t be the first social network to experience a dramatic shift in popularity.

Facebook may already be preparing for this competitive threat, as evidenced by its recent acquisition of Instagram. Still, brand marketers shouldn’t take Facebook’s continued preeminence for granted. They should keep tabs on the way younger audiences are using social media if they want to stay ahead of the competition.